This application is a national phase application of International Application No. PCT/JP00/04737, which was filed on Jul. 14, 2000 and which published in Japanese on Jan. 25, 2001, which in turn claims priority from Japanese Application No. 11/201446, which was filed on Jul. 15, 1999, Japanese Application No. 11/225959, which was filed on Aug. 10, 1999, Japanese Application No. 2000/55552, which was filed on Mar. 1, 2000, Japanese Application No. 2000/108631, which was filed on Apr. 10, 2000, and Japanese Application No. 2000/115588, which was filed on Apr. 17, 2000.
1. Technical Field
The present invention relates to a partial condensate of glycidyl ether group-containing alkoxysilane, a silane-modified resin, compositions thereof and preparation methods thereof.
2. Background Art
In recent years, there is an increasing demand for high-performance cured products of epoxy resin in the field of electric and electronic materials. In particular, the products having higher heat resistance are required.
In order to improve the heat resistance of the cured products of epoxy resin, glass fibers, glass particles, mica and like fillers are added to epoxy resins and curing agents. However, these methods using fillers can not sufficiently improve heat resistance of the cured products of epoxy resin. By these methods, the transparency of the resulting cured products is deteriorated and the interfacial adhesion between the fillers and the epoxy resin is lowered. Thus, the cured products are given insufficient mechanical properties.
Another method for improving the heat resistance of the epoxy resin cured product is to subjecting the epoxy resin to the reaction with a silane coupling agent. However, employment of the silane coupling agent often lowers the glass transition temperature (Tg) of the resin. In addition, the silane coupling agents are usually expensive and not very favorable in terms of the cost.
Japanese Unexamined Patent Publication No. 1996-100107 proposes a method for improving the heat resistance of cured products of epoxy resin compositions by using the complex of an epoxy resin and silica. The complex of an epoxy resin and silica is prepared by adding hydrolyzable alkoxysilane to a solution of a partially cured epoxy resin to further cure the partially cured product; hydrolyzing the alkoxysilane to cause solation; and polycondensing the sol to cause gelation. The heat resistance of the cured product prepared from such complex is improved to some extent compared to the cured product of the epoxy resin by itself. However, water contained in the complex or water and alcohols produced during curing cause voids (air bubbles) inside the cured product. Further, increasing the amount of alkoxysilane to further improve the heat resistance of the cured product results in impaired transparency and whitening of the cured product due to the aggregation of silica produced by sol-gel curing reaction. In addition, solation of a large amount of the alkoxysilane necessitates a large amount of water, which leads to bends and cracks in the cured product.
Meanwhile, there has been reported many studies on silica complexation of various high molecular compounds other than the epoxy resin, in order to improve their heat resistance, toughness, gas barrier properties and the like, by sol-gel curing reaction of hydrolyzable alkoxysilane (Japanese Unexamined Patent Publications No. 1999-92623, No. 1994-192454, No. 1998-168386, No. 1998-152646, No. 1995-118543, etc.). However, in the complex produced by the sol-gel curing reaction, silica is dispersed within the resin by using the hydrogen bonds between the silanol groups produced by hydrolysis of the hydrolyzable alkoxysilane and hydrogen bonding functional groups in a high molecular compound. Therefore, this reaction can not be employed for the high molecular compounds which have no hydrogen bonding functional groups or the high molecular compounds having high Tg, which tend to aggregate.
An object of the present invention is to provide a novel partial condensate of glycidyl ether group-containing alkoxysilane, compositions thereof and preparation methods thereof, the partial condensate being capable of improving the heat resistance and other properties of a cured product by adding to or modifying a resin such as epoxy resin, polyimide resin, polyamide-imide resin, phenol resin and the like.
Another object of the present invention is to provide a silane-modified resin modified with the above partial condensate of glycidyl ether group-containing alkoxysilane, a resin composition thereof and preparation methods thereof.
Other objects and features of the present invention are described below.
The present invention provides a partial condensate of glycidyl ether group-containing alkoxysilane which is obtainable by dealcoholization reaction between glycidol and a partial condensate of alkoxysilane, and preparation methods thereof.
Further, the present invention provides a composition comprising the above partial condensate of glycidyl ether group-containing alkoxysilane.
Further, the present invention provides an alkoxy-containing silane-modified polyimide resin which is prepared by subjecting a polyamic acid and the above partial condensate of glycidyl ether group-containing alkoxysilane to epoxy ring-opening esterification, dehydration and cyclization, and preparation methods thereof.
Further, the present invention provides an alkoxy-containing silane-modified polyamide-imide resin which is prepared by subjecting a polyamide-imide resin having a carboxyl group and/or an acid anhydride group at the end(s) of its molecule and the above partial condensate of glycidyl ether group-containing alkoxysilane to epoxy ring-opening esterification, and preparation methods thereof.
Further, the present invention provides a composition comprising the above silane-modified polyamide-imide resin.
Further, the present invention provides an alkoxy-containing silane-modified phenol resin which is prepared by subjecting a phenol resin and the above partial condensate of glycidyl ether group-containing alkoxysilane to epoxy ring-opening reaction, and preparation methods thereof.
Furthermore, the present invention provides a composition comprising the above silane-modified phenol resin.
The inventors of the present invention conducted extensive research to solve the above-mentioned problems of the prior art. Accordingly, the inventors found the following. According to a resin composition which comprises the above specific partial condensate of glycidyl ether group-containing alkoxysilane and an epoxy resin, or a silane-modified resin, which is a high molecular compound such as polyimide resin, polyamide-imide resin, phenol resin or the like modified with the condensate, it is possible to provide a resin silica hybrid which is a cured product having improved heat resistance and mechanical strength and being free from voids, cracks and the like. The present invention was accomplished based on these findings.
Partial Condensate of Glycidyl Ether Group-containing Alkoxysilane
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention is prepared by dealcoholization reaction between glycidol and the partial condensate of alkoxysilane.
The resulting partial condensate of glycidyl ether group-containing alkoxysilane is typically represented by the following formula (1).
Formula 
wherein R1 represents a glycidyl ether group, a C1-C3 alkoxy group or a group represented by the formula 
[in this formula, R3 represents a glycidyl ether group, a C1-C3 alkoxy group or a group represented by the formula 
(in this formula, R5 represents a glycidyl ether group or a C1-C3 alkoxy group, R6 represents a C1-C8 alkyl group or aryl group, a glycidyl ether group or a C1-C3 alkoxy group), R4 represents a C1-C8 alkyl group or aryl group, a glycidyl ether group, a C1-C3 alkoxy group or a group represented by the above formula (3)], R2 represents a C1-C8 alkyl group or aryl group, a glycidyl ether group, a C1-C3 alkoxy group or a group represented by the above formula (2), when the above R1, R2, R3, R4, R5 and R6 are alkoxy groups, each group may be condensed to form a siloxane bond, and the total number of moles of the glycidyl ether groups contained in R1, R2, R3, R4, R5 and R6 is at least 5 mole % based on the total number of moles of R1, R2, R3, R4, R5 and R6, n, p and q are each an integer of 0 or higher, and the average number of Si is 2 to 300.
In the partial condensate of glycidyl ether group-containing alkoxysilane represented by the formula (1), examples of the C1-C3 alkoxy group represented by R1, R2, R3, R4, R5 and R6 include methoxy group, ethoxy group, n-propoxy group and the like. The number of carbon atoms in the alkoxy group greatly influences the condensation rate of an alkoxysilyl portion of the partial condensate of glycidyl ether group-containing alkoxysilane. Thus, when the curing is carried out at a low temperature or high curing rate is desired, methoxy group is preferable. Further, examples of the C1-C8 alkyl group or aryl group represented by R2, R4 and R6 include methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group, n-hexyl group, cyclohexyl group, n-octyl group, phenyl group, phenethyl group and the like. Although a long-chain alkyl group contributes to improve the flexibility (degree of elongation) of the cured product, it often lowers the glass transition temperature of the resin. For this reason, R2, R4 and R6 are preferably methyl groups in terms of the heat resistance. Further, as mentioned in the above, when the R1, R2, R3, R4, R5 and R6 are alkoxy groups, they may be condensed to form a siloxane bond.
The total number of moles of the glycidyl ether group contained in the above R1, R2, R3, R4, R5 and R6 is at least 5 mole % based on the total number of moles of R1, R2, R3, R4, R5 and R6. All of the groups R1, R2, R3, R4, R5 and R6 (100 mole %) may be the glycidyl ether groups. More specifically, the content of the glycidyl ether group ((the total number of moles of the glycidyl ether groups contained in R1, R2, R3, R4, R5 and R6)/(the total number of moles of the groups R1, R2, R3, R4, R5 and R6)) is 0.05 to 1.
The higher the content of glycidyl ether group, the more polyfunctional the partial condensate of glycidyl ether group-containing alkoxysilane. Hence, in the resin silica hybrid obtained from the silane-modified resin modified with this partial condensate of glycidyl ether group-containing alkoxysilane, since minute silica is uniformly complexed and the transparency and heat resistance of the resulting hybrid are improved, the content of the glycidyl ether group is preferably 0.1 or higher. When the content of the glycidyl ether group is increased, the dealcoholization reaction time between glycidol and partial condensate of alkoxysilane becomes longer. Therefore, the content of the glycidyl ether group is preferable 0.8 or lower.
Each molecule constituting the partial condensate of glycidyl ether group-containing alkoxysilane of the formula (1) does not need to contain the glycidyl ether groups in the above-specified content. However, the glycidyl ether groups need to be contained in the partial condensate of the formula (1) in the above-specified content.
Further, the partial condensate of glycidyl ether group-containing alkoxysilane represented by the formula (1) has the average number of Si in the formula of 2 to 300. Normally, when the average number of Si is high, the partial condensate of glycidyl ether group-containing alkoxysilane tends to have a branched chain such as the group of the formula (2) or the group of the formula (3). The average number of Si is preferably 2 to 100 in terms of the reactivity with glycidol. Further, when the average number of Si is about 2 to 8, the partial condensate has little or no branched structure, and low viscosity which allows easy handling.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention is prepared by the dealcoholization reaction between glycidol and partial condensate of alkoxysilane.
As the above partial condensate of alkoxysilane is used a compound prepared by hydrolyzing and partially condensing the hydrolyzable alkoxysilane represented by the formula
RamSi(ORb)4-mxe2x80x83xe2x80x83(4)
(wherein m represents 0 or 1, Ra is a C1-C8 alkyl group or aryl group, Rb represents a hydrogen atom or a lower alkyl group.) in the presence of an acid or alkali and water. This partial condensate has the average number of Si of 2 to 300.
The partial condensate of alkoxysilane is typically represented by the following formula (5).
Formula 
wherein R7 represents a C1-C3 alkoxy group or the group represented by the formula 
[in this formula, R9 represents a C1-C3 alkoxy group or the group represented by the formula 
(in this formula, R11 represents a C1-C3 alkoxy group, R12 represents a C1-C8 alkyl group or aryl group or a C1-C3 alkoxy group), R10 represents a C1-C8 alkyl group or aryl group, a C1-C3 alkoxy group or the group represented by the above formula (7)], R8 represents a C1-C8 alkyl group or aryl group, a C1-C3 alkoxy group or the group represented by the above formula (6), when the above R7, R8, R9, R10, R11 and R12 are alkoxy groups, they may be condensed to form a siloxane bond, n, p and q are each an integer of 0 or higher, and the average number of Si is 2 to 300.
R1 in the-above formula (1) corresponds to R7 in the formula (5), and likewise R2 to R8, R3 to R9, R4 to R10, R5 to R11, R6 to R12. Specifically, the alkoxy groups of R7 to R12 in the formula (5) and glycidol undergo dealcoholization reaction to form the glycidyl ether groups in R1 to R6 in the formula (1). Accordingly, examples of the alkyl groups or alkoxy groups of R7 to R12, include those of the R1 to R2. Further, as mentioned in the above, when R7 to R12 are alkoxy groups, they may be condensed to form a siloxane bond.
Further, when alkyl group or aryl group is not contained as R8, R10 and R12, the alkoxysilane condensate represented by the formula (5) is a condensate of tetraalkoxysilane, while the alkoxysilane condensate is a condensate of alkyl (or aryl) trialkoxysilane or of a mixture of alkyl(or aryl) trialkoxysilane and tetraalkoxysilane when the alkyl group or aryl group is contained as R8, R10 and R12.
The used ratio of the glycidol and partial condensate of alkoxysilane can be suitably selected so that the content of the glycidyl ether group in the resulting partial condensate of glycidyl ether group-containing alkoxysilane is in the above-specified range. Normally, it is preferable to conduct the dealcoholization reaction between the glycidol and partial condensate of alkoxysilane at a ratio of the hydroxyl equivalent in the glycidol/the alkoxy equivalent in the partial condensate of alkoxysilane=0.05/1 to 3/1 in starting materials. When this ratio of the starting material is too low, the proportion of unreacted partial condensate of alkoxysilane is increased. Therefore, the ratio of the hydroxyl equivalent of the glycidol in the starting material is preferably 0.1 or higher, based on one alkoxy equivalent of the partial condensate of alkoxysilane. Further, when this ratio of the starting materials is too high, the heat resistance of the cured product tends to be lowered by the remaining unreacted glycidol. Thus, the ratio of the hydroxyl equivalent of the glycidol in the starting material is preferably 1 or lower, based on one alkoxy equivalent of the partial condensate of alkoxysilane.
The reaction between the partial condensate of alkoxysilane and glycidol is carried out, for example, by mixing these ingredients, heating the mixture while removing the produced alcohol to cause dealcoholization reaction, and transesterification of silicic acid ester. The reaction temperature is about 50 to 150xc2x0 C., preferably 70 to 110xc2x0 C., and the total reaction time is about 1 to 15 hours.
When the dealcoholization reaction is conducted at a temperature above 150xc2x0 C., the molecular weight of the reaction product is excessively increased by the condensation of alkoxysilane, and the product may disadvantageously undergo thickening and gelation. Further, the reaction temperature of lower than 50xc2x0 C. does not allow alcohol to be removed from the reaction system, and the reaction does not proceed.
In the above dealcoholization reaction, conventional catalysts which do not cause epoxy ring opening may be used in order to promote the reaction. Examples of the catalysts include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, cerium, boron, cadmium, manganese and like metals; oxides, organic acid salts, halides and alkoxides of these metals; and the like. Among them, organotin and tin organoate are particularly preferable. More specifically, dibutyltin dilaurate, tin octoate, etc., are effectively used.
The above reaction can be performed in a solvent. The solvent is not particularly limited insofar as it is an organic solvent which can dissolve the alkoxysilane partial condensate and glycidol. Preferable examples of such organic solvent include dimethylformamide, dimethylacetamide, tetrahydrofuran, methyl ethyl ketone, toluene, xylene and like aprotic polar solvents.
The thus obtained partial condensate of glycidyl ether group-containing alkoxysilane does not need to have the glycidyl ether group in all of their molecules constituting this partial condensate. However, the condensate as a whole needs to have the glycidyl ether group in the above-specified proportion, and may contain unreacted partial condensate of alkoxysilane.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention may be used as a composition comprising the partial condensate and hydrolyzable alkoxysilane and/or its condensate commonly used for sol-gel method, the hydrolyzable alkoxysilane represented by the formula
RcrSi(ORd)4-rxe2x80x83xe2x80x83(8)
(wherein r represents an integer of 0 to 2. Rc represents a lower alkyl group, aryl group or unsaturated hydrocarbon group which may have a functional group directly bonded to Gag a carbon atom, when r is 2, the two Rc""s may be the same or different. Rd""s may be the same or different and each represents a hydrogen atom or a lower alkyl group.).
Examples of the hydrolyzable alkoxysilane of the formula (8) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane and like tetraalkoxysilanes, methyl-trimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane and like trialkoxysilanes, dimethyl dimethoxysilane, dimethyl diethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane and like dialkoxysilanes. Among these compounds, preferable are the partial condensates of alkoxysilane represented by the above formula (5), which are the condensates of tetraalkoxysilanes and/or trialkoxysilanes.
The used amount of the above hydrolyzable alkoxysilane and/or its partial condensate is preferably about 50 parts by weight or lower, based on 1 part of the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention.
In case of the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention which contains the unreacted partial condensate of alkoxysilane, or in the case of the composition which comprises the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention and the hydrolyzable alkoxysilane and/or its partial condensate, the unreacted substances and ingredients can be converted to silica by hydrolysis and polycondensation. In order to promote the hydrolysis and polycondensation, a small amount of water may be added to the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention before use.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention or the composition which comprises the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention and the hydrolyzable alkoxysilane and/or its partial condensate may be used for various applications. For example, they can be favorably used as a curable composition in combination with a curing agent for epoxy resin.
This curable composition may be used in combination with various resins depending on the application. The preferable resin to be used in combination is epoxy resin. Examples of the usable epoxy resins include bisphenol epoxy resins, orthocresol novolac epoxy resin, phenol novolac epoxy resin and like novolac epoxy resin; glycidyl ester epoxy resins obtained by reacting phthalic acid, dimer acid and the like polybasic acids with epichlorohydrin; glycidyl amine epoxy resins obtained by reacting diaminodiphenylmethane, isocyanuric acid and the like polyamines with epichlorohydrin; linear aliphatic epoxy resins, alicyclic epoxy resins and the like obtained by oxidizing an olefin bond with a peracetic acid or like peracids.
Therefore, examples of the application of the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention include a curable composition comprising the partial condensate, the hydrolyzable alkoxysilane and/or its partial condensate, a curing agent for epoxy resin and an epoxy resin. In this case, the partial condensate of glycidyl ether group-containing alkoxysilane and hydrolyzable alkoxysilane and/or its partial condensate are used as additives for epoxy resin. The used amount of the partial condensate of glycidyl ether group-containing alkoxysilane is usually about 1 to 60 parts by weight, based on 100 parts by weight of the epoxy resin.
As the above curing agent for epoxy resin, the curing agents which are usually used as curing agents for epoxy resin can be used without restriction. The useful curing agents include phenol resin curing agent, polyamine curing agent and polycarboxylic acid curing agent. More specifically, examples of the phenol resin curing agents include phenol novolac resin, bisphenol novolac resin, poly p-vinylphenol and the like; examples of the polyamine curing agents include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dicyandiamide, polyamideamine, polyamide resin, ketimine compound, isophorone diamine, m-xylene diamine, m-phenylene diamine, 1,3-bis(aminomethyl)cyclohexane, N-aminoethylpiperazine, 4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diamino-3,3xe2x80x2-diethyl-diphenylmethane, diaminodiphenyl sulfone and the like; examples of the polycarboxylic acid curing agents include phthalic anhydride, tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, hexachloroendomethylene tetrahydrophthalic anhydride and methyl-3,6-endomethylenetetrahydrophthalic anhydride. Among these, the polyamine curing agents are preferable. The polyamine curing agents act to open an epoxy ring for curing, and act catalystically on an alkoxysilyl group, cure the alkoxysilyl group to convert it into silica.
The used amount of the curing agent for epoxy resin is usually such that the equivalent ratio of a functional group having an active hydrogen in the curing agent to an epoxy group (the epoxy group of the partial condensate of glycidyl ether group-containing alkoxysilane or the total amount of this epoxy group and the epoxy group of the epoxy resin) in the curable composition is about 0.2:1 to 1.5:1.
The above curable composition may contain an accelerator to promote the curing reaction between the epoxy group and the curing agent. Examples of the accelerator include 1,8-diaza-bicyclo[5.4.0]undecene-7, triethylenediamine, benzyldimethyl amine, triethanolamine, dimethylaminoethanol, tris(dimethylaminomethyl)phenol and like tertiary amines; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole and like imidazoles; tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine and like organic phosphines; tetraphenylphosphoniumxc2x7 tetraphenylboric acid, 2-ethyl-4-methylimidazolexc2x7tetraphenylboric acid, N-methylmorpholinexc2x7tetraphenylboric acid and like tetraphenylboric acid salts. Preferably, the accelerator is used in an amount of 0.1 to 5 parts by weight, based on 100 parts by weight of the epoxy compound.
The concentration of the above curable composition can be suitably adjusted using a solvent. The solvent may be the same solvent as that used for the preparation of the partial condensate of glycidyl ether group-containing alkoxysilane. Additionally, the above composition may contain, if necessary, fillers, mold releasing agents, surface modifying agents, retardants, viscosity modifiers, plasticizers, antibacterial agents, antimolds, leveling agents, antifoaming agents, coloring agents, stabilizers, coupling agents and the like insofar as it does not lower the effects of the invention.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention may be used as a silane coupling agent for inorganic fiber reinforced resins, filler compounds, adhesives, sealing compounds and like applications for which silane coupling agents have been conventionally used.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention can be suitably used for preparing various silane-modified resins by modifying various high molecular compounds having a functional group which can react with an epoxy group. Further, resinxc2x7silica hybrids can be obtained by curing such silane-modified resins.
Examples of the functional group which can react with an epoxy group include acid anhydride group, carboxyl group, primary amino group, secondary amino group, phenolic hydroxyl group, thiol group and the like. Further, examples of the high molecular compound having these functional groups include polyamide, polythiol, polyaniline, polyamic acid, polyimide, polyamide-imide, polyetherimide, polyester imide, phenol resin, carboxylic acid-terminated polyester, poly(styrene-maleic anhydride), maleated polybutadiene, ethylene-maleic anhydride copolymer, maleic acid-terminated polypropylene, carboxylic acid-terminated butadiene-acrylonitrile copolymer, amine-terminated polyurethane polyurea, ketimine-terminated polyurethane polyurea, polyadipic acid anhydride and like polyacid anhydrides, polyamine-modified epoxy resins and the like.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention is highly effective in modifying the above high molecular compounds, especially the high molecular compounds which do not have a hydrogen bonding functional group and thus are not capable of complexation of silica by sol-gel method and the high molecular compounds which have high Tg and high aggregation properties and like compounds. For example, when the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention is used for modifying the high molecular compounds having an acid anhydride group, such as polyamic acid, polyimide, polyetherimide, polyester imide, maleated polybutadiene, ethylene-maleic anhydride copolymer, maleic acid-terminated polypropylene, polyadipic acid anhydride and like polyacid anhydrides, the resinxc2x7silica hybrids can be favorably obtained by curing the resulting silane-modified resin.
The reaction ratio between the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention and the high molecular compound having the functional group which can react with an epoxy group is not restricted. The reaction ratio is suitably controlled in consideration of the epoxy equivalent of the partial condensate and the equivalent of the functional group of the high molecular compound, so that the resulting silane-modified resin does not undergo gelation. Further, reaction temperature, reaction time and other reaction conditions are not particularly limited. The reaction is preferably carried out at such a temperature that an alkoxysilyl group is condensed (110xc2x0 C. for methoxysilyl group) or at a lower temperature. Further, the above examples of the curing agents for epoxy resin and the accelerators may be used in these reactions.
To the thus obtained silane-modified resin may be further added, if necessary, the hydrolyzable alkoxysilane represented by the formula (8) and/or its condensate, depending on its properties insofar as it does not undergo phase separation. Furthermore, to the silane-modified resin may be added, if necessary, solvents, fillers, mold releasing agents, surface modifying agents, retardants, viscosity modifiers, plasticizers, antibacterial agents, antimolds, leveling agents, antifoaming agents, coloring agents, stabilizers, coupling agents and the like, insofar as it does not deteriorate the effects of the present invention.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention is a novel compound prepared by introducing a glycidyl ether group to the partial condensate of alkoxysilane. The cured product of the partial condensate of the invention has excellent heat resistance. Further, addition of the partial condensate of the invention to epoxy resins and the like can improve the heat resistance of the cured products of the epoxy resins and the like.
The composition comprising the partial condensate of the glycidyl ether group-containing alkoxysilane of the present invention, the hydrolyzable alkoxysilane condensate and an epoxy resin and the like do not cause whitening or the like in its cured product. Further, the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention may be used as a silane coupling agent and the like.
The reaction of the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention with the high molecular compound having the functional group which can react with an epoxy group can produce a silane-modified resin. Therefore, the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention enables the high molecular compounds, with which it was conventionally difficult to form silica hybrids, to produce resinxc2x7silica hybrids.
The partial condensate of glycidyl ether group-containing alkoxysilane of the present invention may be combined with a curing agent for epoxy resin, an epoxy resin and the like and can be suitably used, for example, as various curable compositions. The partial condensate of the invention can react with various resins to produce silane-modified resins and/or their resin compositions. These compositions, for example, are used for various applications such as IC sealing materials, epoxy resin laminates, coating compositions, adhesives, coatings for electric and electronic materials and the like.
Alkoxy-containing Silane-modified Polyimide Resin
One of the silane-modified resins of the present invention, an alkoxy-containing silane-modified polyimide resin is prepared by subjecting a polyamic acid and the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention which is obtained by the dealcoholization reaction between glycidol and the partial condensate of alkoxysilane, to epoxy ring-opening esterification, dehydration and cyclization.
The above polyamic acid can be obtained by reacting a tetracarboxylic acid dianhydride with a diamine in a solvent.
Examples of the tetracarboxylic acid dianhydride include pyromellitic dianhydride, 3,3xe2x80x2,4,4xe2x80x2-biphenyltetracarboxylic acid dianhydride, 2,3,3xe2x80x2,4xe2x80x2-biphenyltetracarboxylic acid dianhydride, 2,2xe2x80x2,3,3xe2x80x2-biphenyltetracarboxylic acid dianhydride, 3,3xe2x80x2,4,4xe2x80x2-benzophenonetetracarboxylic acid dianhydride, 2,2xe2x80x2,3,3xe2x80x2-benzophenonetetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, 2,2-bis(4-(4-aminophenoxy) phenyl)propane dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 2,3,5,6-pyridinetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride and the like conventionally known tetracarboxylic acid dianhydrides. These compounds may be used singly or in combination of two or more kinds.
Examples of the diamine include 4,4xe2x80x2-diaminodiphenylether, 4,4xe2x80x2-diaminodiphenylmethane, 4,4xe2x80x2-diaminodiphenyl sulfone, 4,4xe2x80x2-diaminodiphenylsulfide, benzidine, m-phenylene diamine, p-phenylene diamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, bis(4-aminophenoxyphenyl) sulfone, bis(3-aminophenoxyphenyl)sulfone, bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ether, 1,4-bis(4-aminophenoxy)benzene, 2,2xe2x80x2-dimethyl-4,4xe2x80x2-diaminobiphenyl, 2,2xe2x80x2-diethyl-4,4xe2x80x2-diaminobiphenyl, 3,3xe2x80x2-dimethyl-4,4xe2x80x2-diaminobiphenyl, 3,3xe2x80x2-diethyl-4,4xe2x80x2-diaminobiphenyl, 2,2xe2x80x2,3,3xe2x80x2-tetramethyl-4,4xe2x80x2-diaminobiphenyl, 2,2xe2x80x2,3,3xe2x80x2-tetraethyl-4,4xe2x80x2-diaminobiphenyl, 2,2xe2x80x2-dimethoxy-4,4xe2x80x2-diaminobiphenyl, 3,3xe2x80x2-dimethoxy-4,4xe2x80x2-diaminobiphenyl, 2,2xe2x80x2-dihydroxy-4,4xe2x80x2-diaminobiphenyl, 3,3xe2x80x2-dihydroxy-4,4xe2x80x2-diaminobiphenyl, 2,2xe2x80x2-di(trifluoromethyl)-4,4xe2x80x2-diaminobiphenyl and the like aromatic diamine compounds and the like. These compounds may be used singly or in combination of two or more kinds.
The solvent is not particularly limited insofar as it can dissolve the tetracarboxylic acid dianhydride, the diamine and the partial condensate of glycidyl ether group-containing alkoxysilane. Examples of the solvent include N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethyl sulfoxide, hexamethyl phosphortriamide, dimethylimidazoline, N-acetyl-xcex5-caprolactam and the like.
The molar ratio of the tetracarboxylic acid dianhydride to the diamine in the synthesis reaction of the polyamic acid is preferably from 0.8 to 1.2. When the ratio is lower than 0.8 or higher than 1.2, the molecular weight of the resulting polyamic acid is not sufficiently high.
The thus obtained polyamic acid itself has a carboxyl group, and can cause epoxy ring-opening esterification with the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention. This reaction is usually conducted at about 50 to 130xc2x0 C. for 1 to 15 hours, giving an alkoxy-containing silane-modified polyamic acid. When the reaction temperature is lower than 50xc2x0 C., the progress of the reaction is slow, whereas the reaction temperature is higher than 130xc2x0 C., the alkoxysilyl portions of the partial condensate cause condensation. Thus the temperature lower than 50xc2x0 C. or higher than 130xc2x0 C. is not favorable.
The reaction ratio of the polyamic acid to the partial condensate of glycidyl ether group-containing alkoxysilane in the above reaction is not particularly limited. However, the ratio of the glycidyl ether equivalent of the partial condensate of glycidyl ether group-containing alkoxysilane/the carboxyl equivalent of the polyamic acid is preferably 0.1 to 1.0.
In the reaction between the above polyamic acid and the partial condensate of glycidyl ether group-containing alkoxysilane, a catalyst may be used to promote the reaction. Examples of the catalyst include 1,8-diazabicyclo[5.4.0]undecene-7, triethylenediamine, benzyldimethyl amine, triethanolamine, dimethylaminoethanol, tris(dimethylaminomethyl) phenol and like tertiary amines; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole and like imidazoles; tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine and like organic phosphines; tetraphenylphosphoniumxc2x7tetraphenyl borate, 2-ethyl-4-methylimidazole tetraphenyl borate, N-methylmorpholinexc2x7tetraphenyl borate and like tetraphenyl boron salts and the like. The catalyst is preferably used in an amount of about 0.1 to 5 parts by weight, based on 100 parts by weight of the polyamide-imide resin.
The reaction product obtained by the above reaction has a structure such that the glycidyl ether group of the partial condensate of glycidyl ether group-containing alkoxysilane has underwent epoxy ring opening esterification by the carboxyl group of the polyamic acid. Accordingly, the alkoxy-containing silane-modified polyamic acid produced by this reaction maintains at least 60% of the alkoxy group contained in the partial condensate of glycidyl ether group-containing alkoxysilane, preferably at least 90%.
Furthermore, the above silane-modified polyamic acid may be converted to the desired alkoxy-containing silane-modified polyimide resin by dehydration and cyclization at about 250 to 400xc2x0 C., if necessary, after being molded. At this time, sol-gel reaction and dealcoholization condensation reaction occur at the alkoxysilyl portions, producing polyimidexc2x7silica hybrid.
The above alkoxy-containing silane-modified polyimide resin of the present invention has greatly improved heat resistance, mechanical strength and the like.
This alkoxy-containing silane-modified polyimide resin may contain the various additive mentioned in the above, if necessary, and may be used for the various applications mentioned in the above.
Alkoxy-containing Silane-modified Polyamide-imide Resin
One of the silane-modified resin of the present invention, an alkoxy-containing silane-modified polyamide-imide resin, is prepared by subjecting a polyamide-imide resin having a carboxyl group and/or acid anhydride group at the end(s) of its molecule, and the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention obtained by dealcoholization reaction between glycidol and the partial condensate of alkoxysilane, to epoxy ring-opening esterification.
The above polyamide-imide resin, which has an amide bond and an imide bond in its molecule, is prepared so that it contains a carboxyl group and/or an acid anhydride group at the end(s) of its molecule.
This polyamide-imide resin can be synthesized by condensation reaction between tricarboxylic acids and diisocyanates, or by reacting tricarboxylic acids with diamines to introduce an imide bond to resin chain, and then reacting the reaction product with isocyanates to cause amidation of the product.
Examples of the tricarboxylic acids which constitute the polyamide-imide resin include trimellitic anhydride, butane-1,2,4-tricarboxylic acid, naphthalene-1,2,4-tricarboxylic acid and the like. Examples of the diisocyanates include diphenylmethane-4,4xe2x80x2-diisocyanate (MDI), diphenylether-4,4xe2x80x2-diisocyanate, tolylene diisocyanate, xylene diisocyanate, isophorone diisocyanate and the like. Examples of the diamines include those which correspond to these diisocyanates.
The ratio of the above reaction ingredients in the synthesis of the polyamide-imide resin is not particularly limited insofar as it is in the range which substantially allows a carboxyl group and/or an acid anhydride group to remain at the end(s) of its molecule. Considering the loss of the diisocyanates by the act of the moisture present in the air or in the solvent, it is preferable that the molar ratio of the isocyanate groups to the carboxyl groups and/or acid anhydride groups, or the molar ratio of the amino groups to the carboxyl groups and/or acid anhydride groups is 0.85 or higher but not higher than 1.05.
The molecular weight of the polyamide-imide resin is preferably the weight average molecular weight of not lower than 5000 but lower than 100000, calculated as styrene determined by GPC. The weight average molecular weight of lower than 5000 lowers the elongation rate and flexibility of the film produced from the resin, whereas the weight average molecular weight of higher than 100000 increases the viscosity of the resulting resin, leading to lowered the handling properties of the resin.
In the preparation of the above polyamide-imide resin, dicarboxylic acids and tetracarboxylic acids may be used in combination with the above tricarboxylic acids. These acids may be used in the amount of not higher than 10 mole % of the tricarboxylic acids.
Examples of the dicarboxylic acids which may be used in combination with the tricarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, undecanoic diacid, dodecanoic diacid, tridecanoic diacid, acid anhydrides of these acids and like aliphatic dicarboxylic acids; isophthalic acid, terephthalic acid, diphenylmethane-4,4xe2x80x2-dicarboxylic acid, acid anhydrides of these acids and like aromatic dicarboxylic acids. Examples of the tetracarboxylic acids which may be used in combination with the tricarboxylic acids include diphenylether-3,3xe2x80x2,4,4xe2x80x2-tetracarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, biphenyl-3,3xe2x80x2,4,4xe2x80x2-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid, acid anhydrides of these acids and the like.
The alkoxy-containing silane-modified polyamide-imide resin of the present invention is prepared by reacting the above polyamide-imide resin with the above partial condensate of glycidyl ether group-containing alkoxysilane. This reaction is mainly a ring-opening esterification reaction of epoxy rings between the carboxyl group and/or acid anhydride group of the polyamide-imide resin and the glycidyl ether group of the partial condensate of glycidyl ether group containing-alkoxysilane. In this reaction, the alkoxy group of the partial condensate per se may be possibly consumed by water which may be present in the reaction system or the like. However, the alkoxy group usually does not participate in the ring-opening esterification reaction, and thus remains in the silane-modified polyamide-imide resin in the ratio of 60% or higher. This remaining ratio is preferably 80% or higher.
The above silane-modified polyamide-imide resin is prepared, for example, by mixing the above polyamide-imide resin and the above partial condensate of glycidyl ether group-containing alkoxysilane and heating the mixture to cause ring-opening esterification reaction. The reaction temperature is about 40 to 130xc2x0 C., preferably 70 to 110xc2x0 C. The reaction temperature of lower than 40xc2x0 C. prolongs the reaction time, whereas the reaction temperature of higher than 130xc2x0 C. promotes the side reaction, i.e., condensation reaction between alkoxysilyl portions. Therefore, the reaction temperature outside the range of 40 to 130xc2x0 C. is not favorable. When the reaction temperature is about 40 to 130xc2x0 C., the total reaction time are is usually about 1 to 7 hours.
This reaction is preferably conducted in the presence of a solvent. This solvent is not particularly limited insofar as it is an organic solvent which can dissolve the polyamide-imide resin and the partial condensate of glycidyl ether group-containing alkoxysilane. Examples of such organic solvent include N-methylpyrrolidone, dimethyl formamide, dimethyl acetamide and the like. Further, to these good solvents may be added 30% by weight or less of xylene, toluene and like poor solvents, based on the total amount of the solvents, as far as the polyamide-imide resin and the partial condensate are not deposited.
The method for adding the above solvent to the reaction system is not critical, and may be selected at least one of the following three methods for adding a solvent. (1) The solvent used in the synthesis of the above polyamide-imide resin from the tricarboxylic acid and diisocyanate, or from the tricarboxylic acid and diamine is used as it is. (2) The solvent used in the synthesis of the partial condensate of glycidyl ether group-containing alkoxysilane from the glycidol and the partial condensate of alkoxysilane is used as it is. (3) The solvent is added before the reaction of the above polyamide-imide resin and the above partial condensate of glycidyl ether group-containing alkoxysilane.
In the reaction between the above polyamide-imide resin and the above partial condensate of glycidyl ether group-containing alkoxysilane, a catalyst may be used to promote the reaction. This catalyst may be the same as that used in the reaction between the above polyamic acid and the partial condensate of glycidyl ether group-containing alkoxysilane in the same amount.
In the above-mentioned manner, the silane-modified polyamide-imide resin of the present invention can be obtained. This silane-modified polyamide-imide resin has an alkoxy group derived from the partial condensate of glycidyl ether group-containing alkoxysilane in its molecule. This alkoxy group undergoes sol-gel reaction and dealcoholization condensation reaction by evaporation of solvents, heat treatment or the reaction with water (moisture), forming a mutually bonded cured product. Such cured product has gelated fine silica portions (higher network structure of the siloxane bond).
The silane-modified polyamide-imide resin composition of the present invention is characterized by comprising the above silane-modified polyamide-imide resin. To this resin composition may be added, if desired, conventional polyamide-imide resins, the partial condensate of alkoxysilane, the above partial condensate of glycidyl ether group-containing alkoxysilane of the present invention and the like unless the object of the present invention is departed from.
Usually, the above resin composition is a liquid one having a solid content of about 10 to 40% by weight containing the silane-modified polyamide-imide resin and a medium. Examples of the medium include the good solvents used for the above ring-opening esterification reaction, esters, ketones, alcohols, phenols and like polar solvents. Further, the good solvent may be used in combination with xylene, toluene and like poor solvents.
The amount of the silane-modified polyamide-imide resin in the above resin composition is not particularly limited, and the preferable amount is usually not lower than 50% by weight based on the solid content of the composition.
The silane-modified polyamide-imide resin composition of the present invention may suitably contain, if necessary, fillers, mold releasing agents, surface modifying agents, retardants, viscosity modifiers, plasticizers, antibacterial agents, antimolds, leveling agents, antifoaming agents, coloring agents, stabilizers, coupling agents and the like unless the effects of the present invention are lowered.
The silane-modified polyamide-imide resin composition of the present invention can be applied on various substrate materials by coating, immersing and like methods, and dried by heating to provide a desired cured product. This cured product has silica (SiO2) portions formed by the alkoxysilyl group of the silane-modified polyamide-imide resin, i.e., a higher network structure of a siloxane bond. Therefore, this cured product exhibits high elasticity due to the silica portions. The ratio of the silica portions present in the cured product is not particularly limited. In order to impart high flexibility (elongation rate) to the cured product, the ratio of the silica portions is preferably 30% by weight or lower.
The silane-modified polyamide-imide resin of the present invention and the resin composition may be used for various applications such as heat-resistant fibers, films and like molding materials, IC sealing materials, heat-resistant coating compositions, printed circuited boards, heat-resistant adhesives and the like.
The silane-modified polyamide-imide resin of the present invention and its resin composition demonstrate the prominent effect that they have the conflicting properties such as (1) satisfying mechanical strength and heat resistance; and (2) satisfying flexibility and high elongation rate at the same time. Further, this silane-modified polyamide-imide resin and its composition can achieve high elastic modulus.
Alkoxy-containing Silane-modified Phenol Resin
One of the silane-modified resins of the present invention, an alkoxy-containing silane-modified phenol resin, is prepared by subjecting the phenol resin, and the partial condensate of glycidyl ether group-containing alkoxysilane of the present invention obtained by the dealcoholization reaction between the glycidol and the partial condensate of alkoxysilane, to epoxy ring-opening reaction.
As the phenol resin which forms the alkoxy-containing silane-modified phenol resin of the present invention may be used novolac phenol resins obtainable by reacting phenols with aldehydes in the presence of an acid catalyst, and resol phenol resins obtainable by reacting phenols and aldehydes in the presence of an alkali catalyst. Among them, the resol phenol resin usually contains condensation water, which may cause hydrolysis of the alkoxysilyl portions of the partial condensate of glycidyl ether group-containing alkoxysilane. Thus, the novolac phenol resin is preferably used in the present invention. In particular, when the phenol resinxc2x7silica hybrid cured product having high flexibility is desired, alkylphenol novolac resins, among the phenol novolac resins, prepared from cresol and nonylphenol and the like are preferably used. Normally, the phenol resins having the average phenol nucleus number of about 3 to 8 are preferably used.
Examples of the above phenols include phenol, cresol, xylenol, ethylphenol, isopropylphenol, tertiary butyl phenol, amylphenol, octylphenol, nonylphenol, dodecylphenol, chlorophenol, bromophenol and the like. The positions of the substituents in these phenols are not limited. Examples of the useful formaldehydes include formalin, paraformaldehyde, trioxane, tetraoxane and like formaldehyde-generating substances. Further, conventionally known acidic catalysts or alkali catalysts may be used as the catalyst.
The alkoxy-containing silane-modified phenol resin of the present invention is prepared by subjecting the above phenol resin and the above partial condensate of glycidyl ether group-containing alkoxysilane to epoxy ring-opening reaction. This reaction forms the alkoxy-containing silane-modified phenol resin in which the hydroxyl groups of the phenol resin are partially modified with the partial condensate of glycidyl ether group-containing alkoxysilane.
The used ratio of the phenol resin to the partial condensate of glycidyl ether group-containing alkoxysilane in this reaction is not restricted. Preferably, the equivalent ratio of the glycidyl ether group of the partial condensate of glycidyl ether group-containing alkoxysilane/the hydroxyl group of the phenol resin is in the range of 0.1 to 1. However, when the phenol resin having the average nucleus number of 3 or greater is used, the reaction between the glycidyl ether group and the phenolic hydroxyl group is likely to cause gelation. Therefore, the equivalent ratio of the glycidyl ether group/the hydroxyl group is preferably controlled to be lower than 0.5.
The preparation of the alkoxy-containing silane-modified phenol resin of the present invention is conducted, for example, by mixing the phenol resin and the partial condensate of glycidyl ether group-containing alkoxysilane, heating the mixture to cause epoxy ring-opening reaction. This reaction is preferably performed under substantially anhydrous conditions to prevent the polycondensation of the partial condensate of glycidyl ether group-containing alkoxysilane itself. The main purpose of this reaction is reacting the hydroxyl group of the phenol resin and the epoxy group of the partial condensate of glycidyl ether group-containing alkoxysilane. Thus, it is necessary to inhibit the formation of silica by the sol-gel reaction of the alkoxysilyl portions of the partial condensate of glycidyl ether group-containing alkoxysilane, and the dealcoholization reaction between the alkoxysilyl portions and the phenol resin during the epoxy ring-opening reaction. For this reason, the reaction temperature is about 50 to 120xc2x0 C., preferably 60 to 100xc2x0 C., and the total reaction time is preferably about 1 to 10 hours.
In the above epoxy ring-opening reaction, a conventionally known catalyst may be used to promote the reaction. Examples of the catalyst include 1,8-diaza-bicyclo[5.4.0]undecene-7, triethylenediamine, benzyl-dimethyl amine, triethanolamine, dimethylaminoethanol, tris(dimethylaminomethyl)phenol and like tertiary amines; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methyl-imidazole, 2-heptadecylimidazole and like imidazoles; tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine and like organic phosphines; tetraphenylphosphoniumxc2x7tetraphenyl borate, 2-ethyl-4-methylimidazole - tetraphenyl borate, N-methylmorpholinexc2x7tetraphenyl borate and like tetraphenyl borates and the like. The reaction catalyst is preferably used in an amount of 0.01 to 5 parts by weight, based on 100 parts by weight of the epoxy resin.
The above reaction may be performed in a solvent or without a solvent depending on the application. The solvent is not particularly limited insofar as it can dissolve the phenol resin and the partial condensate of glycidyl ether group-containing alkoxysilane (2). Examples of such solvent include N-methylpyrrolidone, dimethyl formamide, dimethyl acetamide, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, xylene and the like.
The thus obtained alkoxy-containing silane-modified phenol resin has the alkoxy group derived from the partial condensate, and the phenolic hydroxyl group derived from the phenol resin in its molecule, but does not have the epoxy group derived from the glycidol. The content of the alkoxy groups is not critical. The alkoxy groups are necessary for forming a mutually bonded cured product by evaporation of solvents, heat treatment, or reaction with water (moisture) to cause sol-gel reaction and dealcoholization condensation. Therefore, 50 to 95 mole %, preferably 60 to 95 mole % of the alkoxy groups of the partial condensate of glycidyl ether group-containing alkoxysilane is left unreacted in the alkoxy-containing silane-modified phenol resin. Further, the content of this phenolic hydroxyl group is not limited.
This alkoxy-containing silane-modified phenol resin can also be cured by heating by the same reaction mechanism as conventional novolac phenol resins when combined with amines and epoxy resins. When this alkoxy-containing silane-modified phenol resin is cured with amines, or when this alkoxy-containing silane-modified phenol resin and the epoxy resin are used in combination, this alkoxy-containing silane-modified phenol resin needs to have the phenolic hydroxyl group to ensure the sufficient progress of the above reaction. Specifically, 30 to 95 mole %, preferably 60 to 90 mole % of the hydroxyl group of the phenol resin is left unreacted in the alkoxy-containing silane-modified phenol resin.
The cured product obtained from such alkoxy-containing silane-modified phenol resin has gelated fine silica portions (higher network structure of the siloxane bond) derived from the partial condensate of glycidyl ether group-containing alkoxysilane. In addition, the alkoxy-containing silane-modified phenol resin of the present invention comprises, as a main component, the phenol resin in which the hydroxyl groups in the phenol resin are partially modified with silane. The alkoxy-containing silane-modified phenol resin of the present invention may contain the unreacted phenol resin and the partial condensate of alkoxysilane (unreacted substances contained in partial condensate of glycidyl ether group-containing alkoxysilane), the partial condensate of glycidyl ether group-containing alkoxysilane, the solvents and catalysts used in the reaction. Incidentally, the unreacted partial condensate of alkoxysilane and the unreacted partial condensate of glycidyl ether group-containing alkoxysilane undergo hydrolysis and polycondensation and form silica when being cured, and is integrated with the alkoxy-containing silane-modified phenol resin.
The alkoxy-containing silane-modified phenol resin composition of the present invention is characterized by comprising the above silane-modified phenol resin.
This resin composition is usually a liquid one containing the alkoxy-containing silane-modified phenol resin and the solvent, having a curing residue of about 10 to 40% by weight. Examples of the solvent for the resin composition include the good solvents used in the above ring-opening esterification reaction, esters, ketones, alcohols, phenols and like polar solvents. Further, these good solvents may be used in combination with xylene, toluene and like poor solvents.
In the resin composition containing the alkoxy-containing silane-modified phenol resin, the Si content calculated as the weight of silica in the curing residue of this resin composition is preferably 2 to 50% by weight. Herein, by the term xe2x80x9cSi content calculated as the weight of silica in the curing residuexe2x80x9d is meant the percentage by weight of the silica portions in the curing residue when the alkoxysilyl portions of the alkoxy-containing silane-modified phenol resin forms a higher siloxane bond by the sol-gel curing reaction and converted into silica portions by curing, the silica portion being approximately represented by the formula
RetSi(O)(4-t)/2xe2x80x83xe2x80x83(9)
(wherein t is 0 or 1. Re represents a C1-C8 alkyl group or aryl group.). When the Si content is lower than 2% by weight, the heat resistance, strength and like properties are hardly improved, while the Si content is higher than 50% by weight, the cured product becomes too brittle and the strength may be lowered.
Herein, the term xe2x80x9cthe curing residuexe2x80x9d means a solid content remaining after the solvent of the alkoxy-containing silane-modified phenol resin is removed and the alkoxysilyl portions are cured and converted into silica portions.
The concentration of the above resin composition can be suitably controlled with a solvent, depending on its application. The useful solvent is not particularly restricted insofar as it can dissolve the alkoxy-containing silane-modified phenol resin.
In case the amount of silica of the cured product needs to be controlled for the purpose of controlling the dynamic strength and heat resistance of the cured product, the partial condensate of alkoxysilane and the phenol resin may be added to the above alkoxy-containing silane-modified phenol resin composition. Further, the alkoxy-containing silane-modified phenol resin composition may comprise various conventional curing agents used for curing phenol resins. Specifically, suitable curing agent includes hexamethylenetetramine, melamine resin and like amines. Furthermore, the above silane-modified phenol resin composition may contain conventional acidic or basic catalysts, metal catalysts and like catalysts which can cause sol-gel curing or water to aid silica curing reaction at a low temperature. However, when water is added to the resin composition, the amount of water is preferably 0.6 mole or lower per mole of the alkoxy group of the alkoxy-containing silane-modified phenol resin, in light of the viscosity stability of the alkoxy-containing silane-modified phenol resin composition.
Various additives may be added to the above alkoxy-containing silane-modified phenol resin composition insofar as they do not deteriorate the effects of the present invention, if necessary. Examples of the additives include fillers, mold releasing agents, surface modifying agents, retardants, viscosity modifiers, plasticizers, antibacterial agents, antimolds, leveling agents, antifoaming agents, coloring agents, stabilizers, coupling agents and the like.
The alkoxy-containing silane-modified phenol resin of the present invention may be suitably used as a curing agent for epoxy resin. Hence, the alkoxy-containing silane-modified phenol resin of the present invention is added to a conventional epoxy resin in such an amount that the hydroxyl equivalent in this curing agent is about 0.5 to 1.5, based on 1 epoxy equivalent of the epoxy resin, whereby the epoxy resin composition of the present invention can be prepared.
As the epoxy resin for which the curing agent for epoxy resin of the present invention can be applied may be used various conventional epoxy resins. Examples of such epoxy resins include orthocresol novolac epoxy resin, novolac phenol epoxy resin and like novolac epoxy resins; diglycidyl ether epoxy resins derived from bisphenol A, bisphenol F and the like; glycidyl ester epoxy resins obtained by reacting phthalic acid, dimer acid and the like polybasic acids with epichlorohydrin; glycidyl amine epoxy resins obtained by reacting diaminodiphenylmethane, isocyanuric acid and like polyamines with epichlorohydrin; linear aliphatic epoxy resin and alicyclic epoxy resin obtained by oxidizing an olefin bond with peracetic acid and like peracids and the like. These epoxy resins may be used singly or in combination of two or more kinds suitably.
Further, in the epoxy resin composition of the present invention, in order to promote hydrolysis and polycondensation for curing the alkoxysilyl portions of the alkoxy-containing silane-modified phenol resin may be added a catalyst. Examples of the catalyst include a small amount of water, a catalytic amount of formic acid, acetic acid, propionic acid, p-toluenesulfonic acid, methanesulfonic acid and like organic acid catalysts, boric acid, phosphoric acid and like inorganic acid catalysts and alkali catalysts, organotin and tin organoate catalysts. Moreover, the epoxy resin composition of the present invention may contain an accelerator for accelerating the curing reaction between the epoxy resin and the curing agent. As this accelerator may be used the same compounds as used in the preparation of the above alkoxy-containing silane-modified phenol resin. The accelerator is preferably used in an amount of 0.1 to 5 parts by weight, based on 100 parts by weight of the epoxy resin.
The concentration of the epoxy resin composition can be suitably adjusted with a solvent. The useful solvent may be the same as that used for the preparation of the alkoxy-containing silane-modified phenol resin. Additionally, the epoxy resin composition may contain, if necessary, the same additives as used for the preparation of the above alkoxy-containing silane-modified phenol resin composition, for example, fillers, mold releasing agents, surface modifying agents, retardants and the like.
When the above alkoxy-containing silane-modified phenol resin composition and the epoxy resin composition are used as coating compositions and various coating materials, 0 to 150 parts by weight of conventional pigments are added to 100 parts by weight of the curing residue of the alkoxy-containing silane-modified phenol resin composition. This coating composition is applied on a substrate material using spays, coaters and the like conventional coating devices, and then heated preferably at a temperature not lower than 60xc2x0 C. to form a coating film. When the above coating composition is for outdoor use, conventional acidic or basic catalysts, metal catalysts and like catalysts which can cause sol-gel curing are preferably added thereto. The used amount of this catalyst may be suitably selected depending on the activity of the used catalyst. Usually, high-performance catalysts such as p-toluenesulfonic acid, tin octoate and the like are used in a molar concentration of about 0.01 to 5 mole %, low-performance catalysts such as formic acid, acetic acid and the like are used in a molar concentration of about 0.1 to 50 mole %, based on the alkoxy group of the used silane-modified phenol resin. Epoxy resins, alkyd resins, maleated oils and the like may added to the resin composition to further increase the flexibility or toughness of the cured film.
When the alkoxy-containing silane-modified phenol resin composition and the epoxy resin composition are used to prepare molded products, the alkoxy-containing silane-modified phenol resin is synthesized without using solvents, and is combined with the above amine curing agents and the epoxy resins, optionally with curing catalysts, various fillers, various fibers and water to give a resin composition. The molding method is not particularly limited, and may be a conventional method for molding thermosetting resins. Examples of the molding method include compression-molding, transfer molding, injection molding and the like. Considering the dimensional stability of the molded product, not lower than 70%, preferably not lower than 90% of silica curing reaction should have been performed before being placed into the mold to prevent shrinkage of the molded product resulting from the methanol generated by silica curing reaction. Thus, the resin composition is pre-heated at 100 to 150xc2x0 C. before being placed into the mold so that the sol-gel curing reaction which forms the silica portions proceeds. To allow the sol-gel curing reaction to proceed while maintaining the fluidity of this resin, the alkoxy-containing silane-modified phenol resin using o-cresol, nonylphenol and like alkylphenol is preferably used.
The resin composition which uses the alkoxy-containing silane-modified phenol resin of the present invention and the epoxy resin composition containing the alkoxy-containing silane-modified phenol resin as a curing agent for epoxy resin can provide a resinxc2x7silica hybrid which is a cured product being excellent in heat resistance, dynamic strength and free of voids (air bubbles) or the like. These resin compositions and resin silica hybrids are suitably used as IC sealing materials, epoxy resin laminates, coating materials for electricxc2x7electronic materials, coating compositions, inks and like various applications.